Conflict over Male Parentage in Social Insects
Robert L. Hammond1* , Laurent Keller1

1 Department of Ecology and Evolution, Bātiment de Biologie, University of
Lausanne, Lausanne, Switzerland

Mutual policing is an important mechanism that maintains social harmony in
group-living organisms by suppressing the selfish behavior of individuals.
In social insects, workers police one another (worker-policing) by
preventing individual workers from laying eggs that would otherwise develop
into males. Within the framework of Hamilton's rule there are two
explanations for worker-policing behavior. First, if worker reproduction is
cost-free, worker-policing should occur only where workers are more closely
related to queen- than to worker-produced male eggs (relatedness
hypothesis). Second, if there are substantial costs to unchecked worker
reproduction, worker-policing may occur to counteract these costs and
increase colony efficiency (efficiency hypothesis). The first explanation
predicts that patterns of the parentage of males (male parentage) are
associated with relatedness, whereas the latter does not. We have
investigated how male parentage varies with colony kin structure and colony
size in 50 species of ants, bees, and wasps in a phylogenetically controlled
comparative analysis. Our survey revealed that queens produced the majority
of males in most of the species and that workers produced more than half of
the males in less than 10% of species. Moreover, we show that male parentage
does not vary with relatedness as predicted by the relatedness hypothesis.
This indicates that intra- and interspecific variation in male parentage
cannot be accounted for by the relatedness hypothesis alone and that
increased colony efficiency is an important factor responsible for the
evolution of worker-policing. Our study reveals greater harmony and more
complex regulation of reproduction in social insect colonies than that
expected from simple theoretical expectations based on relatedness only.

Full Text at PLoS Biology
http://www.plosbiology.org/plosonline/?request=get-document&doi=10.1371%2Fjournal.pbio.0020248

Posted by
Robert Karl Stonjek
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